Grammar: If you're writing 'if', consider whether it should be 'whether' instead.
Created | Updated Nov 13, 2013
At first glance these two sentences may seem to be saying the same thing:
(1) "Tell me whether you can come."
(2) "Tell me if you can come."
However, on further consideration we can see that in fact they are not. In the first sentence, what the speaker is saying is that he or she requires an answer to the question: "Can you come? Yes or no?"
In the second sentence, the speaker probably wishes to convey the same meaning as in sentence 1, but is in fact saying something different: "If you can come, then I want you to tell me something - not necessarily about your ability or otherwise to come - possibly something about kangaroos or saucepans. And if you can't come, you needn't tell me anything about kangaroos, saucepans or whatever it is I want you to tell me about if you can come."
The word 'if' is commonly used to replace 'whether', but its real role is as an introduction to a conditional clause, and if we're interested in using the English language correctly it shouldn't usurp the role of whether.
Where "whether" would be more appropriate
For example:
"I share your concerns about China but I'm not sure if not watching it will make a difference."
The writer presumably means, "I'm not sure whether not watching it will make a difference." But what she's written implies that her being unsure (about something, possibly to do with saucepans or kangaroos) is conditional upon whether watching it (the Olympics in this case) will make a difference.
"I was just wondering if this is a very local Northern Ireland expression, or if it's more widely used."
Does the fact that the writer is wondering depend on something being a local NI expression? Of course we know that he's trying to say,"I was just wondering whether this is a very local Northern Ireland expression, or whether it's more widely used"
from context and common sense, but by using 'if' instead of 'whether' his meaning is ambiguous. It could be taken to mean, "If this is a very local Northern Ireland expression, then in that case I was just wondering", which admittedly would be a bizarre thing to say.
"I love that SoRB entry on Belming (I Scout-picked it).
I wonder if the OED would publish based on the evidence of a h2g2 entry."
Here again, 'if' should be replaced by 'whether'.
